Disclosed herein is a printing process. More particularly described is a three-dimensional printing process comprising selective laser lithography using curable gellant ink compositions.
Three-dimensional (3D) printing is fast becoming a major industry. Additive manufacturing processes can be used to prepare 3D objects. Additive manufacturing generally uses four main processes. These are stereolithography (SLA), selective laser sintering (SLS), fused deposition modeling (FDM), and multi-jet modeling (MJM). There are advantages and disadvantages to each process. One of the primary challenges in general is that three-dimensional (3D) objects require a support structure to handle 3D objects that require overhangs or unsupported structures prior to curing. SLS addresses this challenge by using the powder in the bed to be the support structure wherever it is required. A major disadvantage with this approach is the slightly powder surface appearance and the need for polishing to provide smooth surfaces, waste of the bed powder, and the requirement for post-build removal of the powder support structure.
SLA and MJM may be more desirable in terms of surface finish, but require support structures built into the overall build that must be removed post-build with baths to dissolve or facilitate washing away of the support. SLA is illustrated generally in FIG. 1. In an SLA process 10, the liquid monomer 12 is deposited into a bath or vat 14 in a small layer and then exposed to ultra-violet (UV) light via a UV laser 16 to cross-link the monomer. The build platform 18 having stereolithography pattern 20 thereon is then lowered such as via elevator 22 capable of Z-axis movement 24 until another layer is ready to be exposed. 26 indicates the resin surface. This process continues until the object is formed. In complex 3D objects where there are overhangs and the like, support materials are required to enable the overhangs. This requires a support material that is both cross-linkable but also removable, such as by solvent wash or physical means. These requirements present a major impediment to the SLA process.
In MJM processes, the liquid monomer is jetted onto a substrate layer by layer, interspersed with a curing step such as by exposure to ultra-violet light. Thus, the 3D object is built up over time. However, again with objects that have overhangs, a support layer that is jettable, curable, and removable after the object has been formed is required.
SLS is illustrated generally in FIG. 2. In an SLS process 200, the powder particles are deposited via a powder delivery system 210 including a powder delivery piston 212 and a roller 214 that is reversibly movable along the direction indicated by the area (and back) along the fabrication powder bed 216 in the build area and then selectively melted layer by layer. Laser 218 and scanner system 220 are directed toward the object being fabricated 222 on fabrication piston 224. Between each step, the new powder is rolled onto the object surface. An advantage to using SLS is that no separate support materials are required. In the area where there is no object, the particles are not sintered by the laser light. With overhangs of the 3D object, the unsintered powder acts as the support material. However, SLS processes present the disadvantages of a slower build speed than other 3D processes and, in most cases, the powder cannot be reused.
Currently available printing processes may be suitable for their intended purposes. However a need remains for improved printing processes. Further, a need remains for an improved three-dimensional printing process. Further, a need remains for an improved three-dimensional printing process which provides improved speed and reduced material waste over currently available processes. Further, a need remains for an improved three-dimensional printing process which overcomes the problems associated with the requirement of providing separate support materials and removing the separate support materials.
The appropriate components and process aspects of the each of the foregoing U.S. Patents and Patent Publications may be selected for the present disclosure in embodiments thereof. Further, throughout this application, various publications, patents, and published patent applications are referred to by an identifying citation. The disclosures of the publications, patents, and published patent applications referenced in this application are hereby incorporated by reference into the present disclosure to more fully describe the state of the art to which this invention pertains.